Bally Walk-In Cooler Error Code A3A: AU3 Temp Sensors Alarm
A3A, AU3 Temp Sensors Alarm, on a Bally walk-in evaporator with the SmartVap+ controller means auxiliary temperature sensor 3 is shorted or open. The manual lists the trigger only. Confirm what the third sensor monitors and call a technician.
Low: an auxiliary sensor has failed, and the main sensors that control cooling are separate.
- Code
- A3A
- Maker
- Bally
- Equipment
- Walk-in coolers & freezers
- Applies to
- SmartVap+ evaporator controller (on-board display / dashboard display), used with Bally walk-in evaporators
What does Bally error code A3A mean?
The third auxiliary input, AU3, can carry a temperature sensor of its own. SmartVap+ keeps checking the sensor's signal, and if it looks shorted or open, it raises the AU3 Temp Sensors Alarm and shows A3A. As with A1A and A2A, the manual's Alarm Status Menu gives only the trigger, with no causes and no repair steps, and it does not say what a sensor on AU3 is used for. That makes it important to find out locally what was installed. Walk-in builders sometimes use extra inputs for discharge air, a second room point or a defrost-related reading, and a missing reading could matter in some of those jobs and not in others. A3A means a sensor circuit is broken. EA3 is a different alarm for the same input when it is used for an external alarm contact.
Affected models and control systems
The SmartVap+ evaporator controller, with its on-board display or dashboard display, on Bally walk-in evaporators that have an auxiliary temperature sensor on AU3. The manual does not say what the sensor is used for.
Code numbers and their meaning can change between control generations. We match the full model and control before acting on a code.
What you may notice
- A3A shows in the active alarm list
- The AU3 temperature value is missing or implausible
- The alarm light is on although the room is stable
Possible causes
Listed in Bally's documentation
- AU3 temperature sensor shorted or open
Other likely causes — what usually sits behind error code A3A on this control. A technician confirms which one it is before any part is replaced.
- Sensor lead broken at the connector after repeated flexing
- Sensor wire chewed or cut where it passes through a wall or conduit
- Moisture in the connector on a cold evaporator
- Input configured for a sensor that was never installed
Safe checks before calling for service
- Ask who set up the walk-in what the AU3 sensor measures and where it is installed.
- Look at any exposed part of the lead for damage, without opening panels or pulling on it.
- Compare the controller's AU3 value, if one shows, with a separate thermometer at that spot.
- Try Clear Alarms (CLA, press and hold) once. If A3A returns, note it for the service call.
How a technician diagnoses error code A3A
- Read active alarms and the AU3 input mode.
- Find the sensor and follow its lead to the controller.
- Measure resistance at the controller and compare with the sensor curve at the actual temperature.
- Check for pinches, rodent damage, moisture and open conductors.
- Replace the sensor or correct the input setting after the test, then clear the alarm.
- The lead may pass near the compressor side or other energized parts that an operator should not reach.
- Whether AU3 should be used for a sensor depends on the site's configuration and records.
How error code A3A differs from similar codes
A3A is the AU3 sensor alarm. A1A and A2A cover the first two inputs, and EA3 is the external alarm for this same input number.
Technical reference
- Document
- SmartVap+ Intuitive Evaporator Control Technology, Operating Instructions (Bulletin B30-SVP-OM-2.05, Part # 1107523)
- Edition
- B30-SVP-OM-2.05, firmware 2.05+, dated 17/09/21
- Models / control
- SmartVap+ evaporator controller (on-board display / dashboard display), used with Bally walk-in evaporators
- Section
- Alarm Status Menu, page 6 of the PDF
- Checked
- October 2026
We use the maker's document to read the code and do not reproduce it. Always confirm the complete model and control before applying these steps.
Related Bally walk-in cooler & freezer error codes
Is A3A the same as EA3?
No. A3A reports a broken sensor circuit. EA3 reports an external alarm input that is active.
Does A3A affect cooling?
The manual does not say. It depends on what the AU3 sensor is used for, which the installer can tell you.
Will it go away after clearing?
Only if the sensor circuit is working again. Otherwise the alarm returns.
Need help with Bally error code A3A?
A technician confirms the cause on site and gives you the price in writing before any work starts.